Summary of Work: In the Membrane Signaling Group, we investigate the biochemical mechanisms that allow the human body to maintain physiological homeostasis, or, in modern terms, the molecular basis of cell communication. In particular we study the signaling pathways that regulate cell function without altering gene expression. Ion channel proteins are the effectors for many of these pathways. We focus on the voltage-dependent channels that are selectively permeable to calcium or to potassium, and we use the patch clamp technique to study channel protein function and regulation at the molecular level in live cells in real time. We are most interested in G protein signaling cascades that regulate ion channel activity through calcium and reversible protein phosphorylation. G proteins are the trans-ducing proteins for the majority of chemical messengers used in cell communication, and receptor proteins that act through G proteins are the most common target of pharmaceuticals used clinically to treat human disease.